base/debug/task_annotator.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/debug/task_annotator.h"
   6
   7 #include "base/debug/alias.h"
   8 #include "base/pending_task.h"
   9 #include "base/trace_event/trace_event.h"
  10 #include "base/tracked_objects.h"
  11
  12 namespace base {
  13 namespace debug {
  14
  15 TaskAnnotator::TaskAnnotator() {
  16 }
  17
  18 TaskAnnotator::~TaskAnnotator() {
  19 }
  20
  21 void TaskAnnotator::DidQueueTask(const char* queue_function,
  22                                  const PendingTask& pending_task) {
  23   TRACE_EVENT_FLOW_BEGIN0(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
  24                           queue_function,
  25                           TRACE_ID_MANGLE(GetTaskTraceID(pending_task)));
  26 }
  27
  28 void TaskAnnotator::RunTask(const char* queue_function,
  29                             const PendingTask& pending_task) {
  30   tracked_objects::TaskStopwatch stopwatch;
  31   stopwatch.Start();
  32   tracked_objects::Duration queue_duration =
  33       stopwatch.StartTime() - pending_task.EffectiveTimePosted();
  34
  35   TRACE_EVENT_FLOW_END1(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
  36                         queue_function,
  37                         TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
  38                         "queue_duration",
  39                         queue_duration.InMilliseconds());
  40
  41   // Before running the task, store the program counter where it was posted
  42   // and deliberately alias it to ensure it is on the stack if the task
  43   // crashes. Be careful not to assume that the variable itself will have the
  44   // expected value when displayed by the optimizer in an optimized build.
  45   // Look at a memory dump of the stack.
  46   const void* program_counter = pending_task.posted_from.program_counter();
  47   debug::Alias(&program_counter);
  48
  49   pending_task.task.Run();
  50
  51   stopwatch.Stop();
  52   tracked_objects::ThreadData::TallyRunOnNamedThreadIfTracking(
  53       pending_task, stopwatch);
  54 }
  55
  56 uint64 TaskAnnotator::GetTaskTraceID(const PendingTask& task) const {
  57   return (static_cast<uint64>(task.sequence_num) << 32) |
  58          ((static_cast<uint64>(reinterpret_cast<intptr_t>(this)) << 32) >> 32);
  59 }
  60
  61 }  // namespace debug
  62 }  // namespace base